The invention concerns a device for bidirectional transferring of audio and/or video signals, in particular in the context of sound and/or image reports.
Devices of the above-mentioned type are known. One known device displays means for providing an audio input signal. The means is connected to a transmission and/or reception device for transmitting the audio signal and/or receiving a audio reception signal. In the known device the transmission and/or reception equipment is designed as ISDN equipment. The application possibilities of the known device are limited to the extent that the operator is dependent on the presence of an ISDN line in the fixed network. If need be, the report to be transferred must be intermediately stored on a storage medium. The storage medium, with the report stored on it, is brought to a device that is connected to an ISDN line. The report is transferred from the storage medium to the device and transmitted via the ISDN line.
In another known device, the transmission and/or reception equipment is designed as a device for connection to a GSM telephone. The connection to the GSM telephone is complicated. In order to transmit with high sound quality, the report must first be intermediately stored on a storage medium. This is due to the fact that when transferring the report via a GSM telephone the transfer rate is low and thus the transferring of the report can be of longer duration than the report itself.
The object forming the basis of the invention is to further develop the known device for bidirectional transferring of audio and/or video signals in such a way that the application possibilities are greatly expanded relative to the prior art.
This object is achieved through a device for bidirectional transferring of audio and/or video signals, in particular in the context of sound and/or image reports, preferably for a real-time transfer, with the following features:
at least one means for providing an audio input signal
a first mixing device that is connected to the means for providing an audio input signal and is intended for output of a mixed audio transmission signal
a transmission and/or reception device coupled to the first mixing device for transmitting the mixed audio transmission signal and/or receiving an audio reception signal
a control device coupled to the first mixing device for controlling the first mixing device
a second mixing device (30)
a compression and/or decompression device for compressing the mixed audio transmission signal or decompression of the audio reception signal, which device is coupled to the first mixing device for taking up the mixed audio transmission signal or, as the case may be, to at least one second mixing device for delivery of a decompressed audio reception signal, and to the transmission and/or reception device for delivery of a compressed audio transmission signal or, as the case may be, for taking up the audio reception signal
at least one means connected to the second mixing device for reproducing an audio output signal, which in particular presents the decompressed audio reception signal
in this device, as a transfer channel provision is made for at least one mobile radio and/or mobile telephone network channel
With the invention, one obtains a device for bidirectional transferring of audio and/or video signals, which device""s application possibilities, in particular in the context of sound and/or image reports, are quite manifold. The device according to the invention is especially simple to operate. Through the mobile radio or mobile telephone channel, the transfer can take place independently of a fixed network. Thus, the device makes possible an application that is to a great degree untied to location. By means of the device, the report can be transferred in real time at a high level of quality. Beyond this, the device makes possible, during the reproduction of the report, an interactive inclusion of the receiver of the report.
The transmission and/or reception device is intended forxe2x80x94preferably independentxe2x80x94transmitting and/or receiving of the compressed audio transmission signal or audio reception signal on several transfer channels, which preferably have the same importance. If necessary, by means of the device video signals and/or other signals relevant to a report can also be transferred, transmitted, and/or received. An advantage of this form of embodiment of the invention is the fact that a rate of transfer that amounts to many times that of a single transfer channel becomes possible. In the case of a form of embodiment that is to be preferred, according to which the transfer can take place on the transfer channels independently of each other, an especially high degree of stability of the transfer is ensured, even if, during the transfer, a (temporary) loss of one or more of the transfer channels should occur. Depending on the compressed audio transmission signal to be transmitted and the audio reception signal to be received, the number and/or type of the transfer channels intended for the transfer differ from the number and/or type of the transfer channels intended for the reception. In this form of embodiment, by means of an adapting of the number and/or type of the transfer channels to the present requirements, the transfer channels are optimally used to capacity, in particular in order to make possible a transfer in real time while using the lowest possible number of transfer channels.
Preferably, the device displays a first channel-control device for selecting one or several transfer channels. If need be, the first channel-control device puts the data of the compressed audio transmission signal into packets. The first channel-control device then distributes the data packets over the transfer channels. The first channel-control device is placed between the compression device and the transmission device. In this form of embodiment of the invention, the first channel-control device ensures an especially simple transfer, even when the data of the audio signal is transmitted in packeted and/or compressed form. Preferably, a second channel-control device is placed between the receiving device and the decompression device and is intended to reconstruct the audio reception signal when the possibly data-packed audio reception signal is received on more than one transfer channel.
The transmission and/or reception device is designed for connection to an antenna, by means of which the compressed audio transmission signal and/or the audio reception signal are transmitted or received, respectively, on the transfer channel or channels. Preferably, the device itself is equipped with the antenna, in order to ensure an especially high degree of independence of the transmission and/or reception operation.
Preferably, the device displays an A/D converter, which at a minimum is placed between the first means for obtaining the audio input signal and the first mixing device. The device according to the invention further displays a D/A converter, which is placed between the second mixing device and the means for reproducing the audio output signal. The A/D converter is intended for providing a digital audio input signal, and the D/A converter for providing an analog audio output signal. The device displays an output port for a digital outputting of the audio signals. Especially preferred is a form of embodiment according to which the output port has a sampling-rate converter for converting the bit rate of the audio signals. A still further improved form of embodiment displays means for dynamically adapting the bit rate of the audio signals, that is to say the data rate. With the dynamic adapting, an especially high degree of flexibility is achieved with respect to the connection of a digital reproduction apparatus to the output port.
In another form of embodiment of the invention, the device displays signal-level limiting device for controlling the level of the audio input signal, which limiting device is placed between the means for obtaining the audio input signal and the first mixing device. The signal-level limiting device serves in particular to avoid an overmodulation of an obtained audio input signal. The device further displays a volume-control device for controlling the level of the audio output signal, which control device is placed between the mixing device and the means for reproducing the audio output signal. The volume-control device makes possible a control of the volume of the audio output signal.
The control device for controlling the first mixing device displays a program and/or data memory, an image-viewing apparatus, an input device, and preferably an interface to a computer and/or a computer network. In this form of embodiment of the invention, there exists the possibility of integrating the device completely into an interactive computer-media network. Preferably, the device also displays a mass storage for storing away the audio signals. The mass storage is controllable by the control device. In a further form of embodiment of the invention, the control device indicates on the image-viewing apparatus the signal level of the audio signal. In one form of embodiment of the invention, the control device is intended to control the second mixing device.
Especially preferred is a form of embodiment in which the entire device or at least a part of the device is sealed against water spray and/or is designed to be received in a small case. In this form of embodiment, the device according to the invention is transportable and is impervious to influences of weather such as rain, humidity, or strong solar radiation.
The mobile device, in an especially compact form of embodiment, is mountable on a camera or is firmly attached to the camera. This mobile device is suitable for transferring image data that is captured by the camera.
In an especially preferred form of embodiment, the mobile device is integrated into an acoustic monitoring system and programmed in such a manner that the device automatically establishes contact with a base station when the monitoring system registers a predetermined event. When the contact with the base station is set up, the mobile device transfers audio signals picked up in its surrounding area. The mobile device is also suited to reproducing and transferring audio signals that were picked up, for example, immediately prior to the occurrence of the predetermined event and whose associated audio data were stored in the mass storage.
Both and mobile elements and the base stations have individual telephone numbers and are thus accessible straightforwardly and selectively from any telephone line whatever. This is especially advantageous in the context of software updates. The carrying out of the latter can take place from a central location, for example directly from the producer, according to the wishes of the operator. Considering all of the devices in operation, this will lead to the fact that in the course of time uniform software standards will no longer be present and in use. In particular upon changes in the audio-compression processes, this can lead to incompatibilities, since in principle each mobile element must be able to work together with each base station, no matter where the latter is located.
According to the invention, this problem can be solved by the fact that provision is made for a data bank for storing of audio-compression algorithms and for a selection device, coupled to the compression and/or decompression device, for selecting a compression or decompression algorithm suitable for the transmitting of an audio transmission signal and/or the receiving of and audio reception signal. With this embodiment, which incidentally also forms an independent inventive concept, the possible audio-compression algorithms are accordingly pre-loaded in the base stations and/or the mobile elements in the form of a data bank. Then, when contact is established, the devices involved settle on the best commonly available process.
The GSM standard, like other mobile phone standards, allows no monitoring of the field strength while the data are being transferred. For this reason, no information is available concerning how secure the transfer actually is.
Thus, in a further preferred embodiment, which alternatively also forms an independent inventive concept, provision is made for monitoring the field strength of the transmitted audio transmission signal and/or the received audio reception signal.
In a further development of this embodiment, a specific quality criterion is created on the basis of the continuous data stream by having the error-monitoring device on the transmitter end provide the audio transmission signal with additional information, and on the receiver end evaluate the errors occurring in the transfer of this information and draw up corresponding error information. In this way, an evaluation of the number of errors occurring is possible on the receiver end. To achieve the purpose, the data stream should be provided with additional information that enables an evaluation on the receiver end of the number of bit-errors occurring. Possibilities here are, for example, methods such as checksum formation, Reed-Solomon coding, or the like.
As was already touched upon above, advantageously several transfer channels should be used in order to have a sufficient channel capacity available; in this, preferably all of the channels have the same importance. However, it has been shown that, even when the antennas of the transmitter and/or receiver device are arranged so that they neighbor each other relatively closely, a clear difference with respect to the security of the transfer can be observed in the transfer channels. Beyond this, the quality over time in all of the transfer channels fluctuates independently of each other, in particular when the mobile element concerned is in motion. One transfer channel whose transfer quality was just now still quite good, suddenly goes bad, and the transfer quality of another channel suddenly becomes dearly better. In extreme cases, contact can even be completely broken, which causes a collapse of the entire transfer.
In order to solve or at least mitigate this problem, it is proposed that the compression and/or decompression device compress the audio transmission signal by means of an audio-compression algorithm that consists of a basic layer and at least one enhancement layer, which layers are transferred in at least one transfer channel; in this, the first channel-control device appropriately assigns to each transfer channel the data of one layer, so that in each case the data of the layer are transferred in one transfer channel. Accordingly, in this embodiment, which incidentally also represents an independent inventive concept, an audio-compression algorithm is first selected, which algorithm consists of a so-called base layer and at least one additional so-called xe2x80x9cenhancement layerxe2x80x9d. These algorithms are formed by a suitable combination of physio-acoustic and predictive coding strategies, such as, for example, CELP and AAC processes. In this, the data streams of the respective layers are, as mentioned, to be chosen so that they can be transferred in a single mobile-radio channel. On the receiver end, the base layer is always necessary in order to decode an audio reception signal. The more enhancement layers are transferred, the better the audio quality of the decoded audio reception signal is.
In a further development of the embodiment described above, the first channel-control device, depending on the error information obtained from the error-monitoring device, selects the transfer channels in such a manner that the base layer is transferred on the transfer channel with the best quality, and preferably, in the case of several enhancement layers, the first enhancement layer is transferred on the transfer channel with the second-best quality, while the remaining enhancement layers are transferred according to their order on a transfer channel with the next-best quality in each case. Accordingly, with this further development a prioritization of the channels on the basis of quality can be carried out, which is obviously only possible when the error information is sent back from the error-monitoring device to the transmitter. Thus, over the best channel the base layer is transferred, over the second-best the first enhancement layer, and so on. Such a measure is especially advantageous when the assignation of the layers to the transfer channels is changed or adapted depending on the momentary situation. On the receiver end one is then able, even in the case of large errors, and particularly at high bit-error rates or when some of the channels have dropped out completely, to at least carry out a decoding of the audio signal via the base layer. The quality changes with the number of data channels available, but in general, with this embodiment even in very unfavorable transfer conditions it is still possible to establish contact.
At this point, for the sake of completeness it should be mentioned that the term xe2x80x9caudio signalxe2x80x9d used here also stands for data signals of all types, thus for signals that, in addition to an audio portion, also contain other data or if necessary can also consist exclusively of other types of data.